holy_calamity writes "UK researchers have developed software that represents a handset's battery life by using a phone's speaker and vibrator to make a device feel and sound like it contains liquid. You give it a shake to find out how much is left. The same technique can be used to represent new messages by simulating balls rattling around inside a box. It runs on recent Nokias with accelerometers; video from the researchers explains it well."
What a bizarrely fun idea.